Flexible Tube Protected Against Vibrations

ABSTRACT

The invention concerns a flexible tube ( 1 ) comprising a corrugated pipe ( 2 ) around which are mounted a pressure resistant braid ( 9 ) of tubular shape made of an adapted material as well as an outer tubular mechanical protection ( 13 ). The invention is characterized in that it comprises a tubular antifriction braid ( 6 ) arranged between the corrugated pipe and the pressure resistant braid, said antifriction braid being made of an adapted material whereof the hardness and/or the friction coefficient are lower than those of the material used for making the pressure resistant braid and at least one tubular damping layer ( 12 ) arranged between the pressure resistant braid and the outer mechanical protection.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a flexible tube used in the field ofindustry, particularly in the field of energy for transporting hazardousor non-hazardous-fluids.

BRIEF DESCRIPTION OF RELATED ART

It is already known practice for gas turbines to be equipped withflexible tubes of this type. To do that, each flexible tube may quitesimply consist of a flexible pipe inserted inside a sheath made ofstainless steel.

A more elaborate flexible tube with enhanced protection against stressesexerted from the outside and liable to damage it has also been proposed.A flexible tube such as this usually consists of a corrugated pipearound which there are attached, in succession, on the one hand, one ortwo pressure-resistant braids of tubular shape made of stainless steeland, on the other hand, an external mechanical protection, also oftubular shape.

Nonetheless, a flexible tube such as this is very highly stressed interms of vibration during operation and the ensuing relativedisplacement between the pressure-resistant braid and the corrugatedpipe causes premature wear of the crests of the corrugations of thecorrugated pipe. In addition, the relative displacement of the externalmechanical protection with respect to the pressure-resistant braidfurther increases the risk of premature wear of the flexible pipe in asmuch as the external mechanical protection, under the effect of thevibrational stresses, is liable to damage the pressure-resistant braid,or even the corrugated pipe itself, via said pressure-resistant braid.

BRIEF SUMMARY OF THE INVENTION

The invention solves the abovementioned problem and for that reason thepresent invention comprises in a flexible tube intended in particularfor transporting hazardous or non-hazardous fluids, this flexible tubecomprising an internal corrugated pipe around which there are attachedat least one pressure-resistant braid of tubular shape made of asuitable material and an external mechanical protection of tubularshape, characterized in that it comprises, on the one hand, anantifriction braid of tubular shape positioned between the corrugatedpipe and the pressure-resistant braid, said antifriction braid beingmade of a suitable material of which the hardness and/or the coefficientof friction are lower than those of the material used to make thepressure-resistant braid and, on the other hand, at least one dampingsheath positioned between the pressure-resistant braid and the externalmechanical protection.

Thus, in a flexible tube according to the invention, incorporating atleast one damping sheath allows the relative displacements generatedwithin the flexible tube under the effect of the vibrational stresses tobe minimized to a great extent and therefore plays a part in lengtheningthe life of the various components. The “damping sheath(s)/antifrictionbraid” coupling allows a more effective means of combating prematurewear of the flexible tube, notably by protecting the crests of thecorrugations of the corrugated pipe from any contact with the stainlesssteel pressure-resistant braid.

In a flexible tube according to the present invention, the corrugatedpipe may have parallel or helical corrugations.

Advantageously, the corrugated pipe is made of a material chosen fromthe group formed of stainless steels and nickel-based alloys.

Advantageously also, the antifriction braid is made of material chosenfrom the group formed of copper-based alloys such as bronze for example,natural fibers and synthetic fibers. The natural fibers and thesynthetic fibers may, for example, comprise fiberglass and of Kevlar®,respectively.

As a preference, each pressure-resistant braid is made of stainlesssteel.

As a preference also, each damping sheath is made of a fiberglass braidor a fiberglass knit coated with silicone, or alternatively, from someother equivalent material.

In one preferred embodiment of the invention, the external mechanicalprotection comprises an interlocked pipe made of stainless or some othersteel.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood with the aid of the detaileddescription which is given hereinbelow with reference to the attacheddrawing in which:

FIG. 1 is, an overall view of a flexible tube according to theinvention, omitting part of the external mechanical protection;

FIG. 2 is a partial view in longitudinal section at one end of theflexible tube depicted in FIG. 1;

FIG. 3 is a view in section on 3-3 of the flexible tube depicted in FIG.2;

FIG. 4 is a section on 4-4 of the flexible tube depicted in FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

A flexible tube 1 according to the invention, as depicted in FIGS. 1 to4, is obtained from a corrugated pipe 2 with parallel corrugations 3which is made of stainless steel and welded at each of its two ends 4 toa coupling 5.

An antifriction braid 6 made of bronze is then slipped along thecorrugated pipe 2, this antifriction braid 6 being of tubular shape andhaving an internal diameter slightly larger than the largest diameter ofthe corrugated pipe 2, at a length substantially equal to that of saidcorrugated pipe 2. More specifically, each of the two ends of thisantifriction braid 6 is crimped into a recess 7 exhibited by thecorresponding coupling 5 and is held in this position by virtue of aclamping collar 8 housed in the recess 7.

A pressure-resistant braid 9 made of stainless steel is then slid alongthe antifriction braid 6. This pressure-resistant braid 9 is designed tohave an internal diameter slightly larger than the external diameter ofthe antifriction braid 6 and a length substantially equal to that ofsaid antifriction braid 6. A retaining ring 11 may be slipped onto eachof the two ends of the pressure-resistant braid 9, saidpressure-resistant braid 9 and each retaining ring 11 then possiblybeing welded to the external lateral face 10 of the correspondingcoupling 5.

A damping sheath 12, preferably made of a silicone-coated fiberglassknit and having a thickness preferably ranging between 3 and 4 mm, isthen slipped along the pressure-resistant braid 9 so as to butt againstthe retaining ring 11.

Finally, an external mechanical protection, produced in the form of astainless steel interlocked pipe 13 with a compensation ring 14 at eachof its two ends is slipped around the damping sheath 12. Morespecifically, an external retaining ring 15 is slipped over each of thetwo ends of the interlocked pipe 13 and the latter, together with itscompensation rings 14, is finally welded, at each of its two ends, tothe retaining rings 15 and to the external lateral face 10 of thecouplings 5.

Thus, in a tube according to the invention, since the crests of thecorrugations 3 of the corrugated pipe 2 are placed in contact with theantifriction braid 6 which is made of a material the hardness and/orcoefficient of friction of which are lower than those than those of thematerial used to male the pressure-resistant braid 9, it then followsthat the wear phenomenon is largely reduced. It is reduced still furtherby virtue of the damping sheath 12 which minimizes the relativedisplacements of the various components with respect to one another as aresult of the vibrational stresses to which the flexible tube 1 issubjected. By way of example, it has been found that a flexible tube 1according to the invention, equipped with such a “dampingsheath(s)/antifriction braid” combination could have a life twenty timeslonger than that of a flexible pipe conventionally used.

Although the invention has been described in conjunction with someparticular exemplary embodiments, it is quite clear that it is not inany way restricted thereto and that it includes all technicalequivalents of the means described and combinations thereof where thesefall within the scope of the invention.

1. A flexible tube for transporting hazardous or non-hazardous fluids,comprising: an internal corrugated pipe around which there is attachedat least one pressure-resistant braid of tubular shape made of asuitable material and an external mechanical protection of tubularshape; an antifriction braid of tubular shape positioned between thecorrugated pipe and the pressure-resistant braid, wherein saidantifriction braid is made of a suitable material of which a hardnessand/or a coefficient of friction are lower than those of the materialused to make the pressure-resistant braid; and at least one dampingsheath positioned between the pressure-resistant braid and the externalmechanical protection.
 2. The flexible tube as claimed in claim 1,wherein the corrugated pipe has parallel or helical corrugations.
 3. Theflexible pipe as claimed in claim 1, wherein the corrugated pipe is madeof a material comprising at least one of stainless steels andnickel-based alloys.
 4. The flexible tube as claimed in of claim 1,wherein the antifriction braid is made of material comprising at leastone of copper-based alloys, natural fibers and synthetic fibers.
 5. Theflexible tube as claimed in claim 1, wherein each pressure-resistantbraid is made of stainless steel.
 6. The flexible tube as claimed inclaim 1, wherein each damping sheath is made of a fiberglass braid or afiberglass knit coated with silicone.
 7. The flexible tube as claimed inof claim 1, wherein the external mechanical protection comprises aninterlocked piped made of stainless steel or some other material.